The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
The seat provided in transportation devices such as a vehicle includes a seat back for supporting the upper body of the passenger, a seat cushion for supporting the lower body such as the buttocks and thighs, and a headrest for supporting the back of the head, wherein at a junction of the seat back and the seat cushion, a reclining device is mounted, which allows the angle of the seat back to be adjusted relative to the seat cushion.
The reclining device is divided into a manual-type reclining device, in which the angle of the seat back is adjusted by the passenger manipulating a lever, and a power-type reclining device, which is automatically operated by the power of a motor through manipulating a switch, and all reclining devices, regardless of how they work, have strong coupling between components during the reclining operation to maintain passenger comfort and provide passenger safety.
In other words, the reclining device includes a component coupled with the seat back and a component coupled with the seat cushion and the two components exert a strong engagement force during the reclining operation. If the seat back has a weak engagement force, the angle of the seat back may be easily changed even with minor impact. In this case, the angle of the seat back is changed when an impact occurs, so that the passenger is injured.
As described above, in order for the reclining device to have a strong engagement force, clearance occurrence between components that are engaged with each other should be inhibited as much as possible. Further, in order to inhibit the seat back from moving as much as possible when the vehicle unstably moves under seated conditions, the operational clearance occurrence should be inhibited as much as possible in the locked state.
Meanwhile, in order to remove clearance in the locked state, there has been disclosed a document of Korean Patent Application Publication No. 10-2007-0032732 A, which is configured such that a pawl that is pushed by a cam rotated at the center and engaged with an external gear is divided into two parts, and the two divided pawls simultaneously come into contact with the cam so as to be pressed by the support of the cam.
However, in the above conventional configuration, the second pawl is pressed in the state where the first pawl is engaged with the external gear, thereby removing a clearance using principle of a wedge, wherein the second pawl functioning as the wedge is slightly pushed and moved, whereby the first pawl is also moved to be engaged. Accordingly, the first and second pawls are moved in real time during the process of engagement and clearance removal, so unless the cam that presses the pawl is elaborately designed, the wedge may be weak or the engagement may become loose.
The conventional configuration is further problematic in that it is difficult to guarantee the durability against clearance when any one of the first and second pawls is worn by repetitive use.